The present invention relates to a mounting arrangement for a spindle, and more particularly to a mounting arrangement for a spindle which is subject to axially directed forces.
Many spindles, particularly tail spindles, are subject to axially directed forces. In such cases, special problems occur with respect to the axial forces which are transmitted to the spindle bearings, and other problems concern the problem of preventing the rotation of the spindle in an out-of-round manner, and the adjustment of the bearing play.
It is known from the prior art to provide two or three roller bearings for the spindle in order to withstand the axially acting forces. These roller bearings must be precisely coordinated with reference to one another, a task which requires a great skill and substantial time. Despite this, difficulties still occur because the axial forces which are transmitted to and must be absorbed by any particular one of the bearings of the set cannot be determined with any degree of exactitude.
In the case of tail spindles it is known to absorb axial forces acting upon them in that the rear end of the spindle is configurated as a piston which extends into a cylinder chamber, an annular seal being provided, to admit pressure fluid into the cylinder chamber to act upon the piston-portion of the spindle so as to counteract the axial force acting upon the spindle and to release the spindle bearing which is subject to this axial force. In this prior-art construction the rear spindle bearing has a cylindrical projection formed at the end of the piston portion and located within the pressure chamber. Since a relatively large amount of hydraulic fluid travels through this chamber, the rear spindle bearing tends to be heated by this fluid, particularly when the spindle rotates at higher speeds, and the oil in the bearing itself becomes heated. This is evidently disadvantageous, as is the further fact that the extent to which bearings can be relieved in this manner is either constant and therefore cannot be adjusted or particular fluctuations in the axial force acting upon the spindle, or else it must be re-adjusted porportional to the axial force acting upon the spindle, each and every time the force varies, by means of a pressure regulating valve.
This prior-art arrangement is therefore also not satisfactory, and neither are other approaches which have been suggested in the prior art but have not led to a satisfactory elimination of the problems resulting from the action of axially directed forces upon a respective spindle.